Andrew LeFevre

The checks were added such that nodes with hostnames that were previously allowed shouldn't be affected at all, the checks are only done at the ~~heartbeat input point~~ EICE discovery...

Got approval from @r0mant issue a warning in v17 and hard reject invalid hostnames in v18. Added a warning here, will open a PR to add to the v17 changelog...

Thanks for the idea @fspmarshall, that's a much better approach than evicting nodes. I added a periodic global notification sent to users that can update nodes, let me know if...

@rosstimothy added regression test

https://github.com/gravitational/teleport/actions/runs/6425075568/job/17446995130 ``` integration_test.go:4739: Error Trace: /__w/teleport/teleport/integration/integration_test.go:4739 Error: Received unexpected error: exit status 255 Test: TestIntegrations/ControlMaster/recording_mode=node Messages: stderr="kex_exchange_identification: Connection closed by remote host\r\nConnection closed by UNKNOWN port 65535\r\n" ```